[Echocardiographic study of left ventricular motion in cases with acute left ventricular diastolic volume...

M-mode and two-dimensional echocardiography were performed to investigate the motion of the interventricular septum (IVS) and posterior wall (PW) in cases with pure mitral (MI) or aortic (AI) insufficiency. Subjects were classified into four groups; 15 cases with chorda rupture or floppy mitral valve (acute MI), four with AI of acute onset (acute AI), 17 with chronic MI including rheumatic MI, mitral valve prolapse syndrome, and 11 with chronic AI. There wee no differences of left ventricular dimension (LVDI), stroke volume (SV), ejection fraction (EF) and cardiac output (CI) between acute and chronic MI, and between acute and chronic AI, although LVDI and CI were increased in all groups. The ratio of the amplitude of IVS to PW excursion was significantly increased in cases with LV dilation due to acute MI or AI, compared with that in chronic MI or AI. This ratio had a linear relationship with LVDI in acute volume overload, but in chronic volume overload, it was constantly 1.0 or less. The mechanism of the increased septal motion in acute MI or AI is still unknown, but it appears to reflect the intact and contractile septum which adapts to volume overload more readily than the posterior wall. It is probably because the posterior wall is prevented from distension by the pericardium. On the other hand, in chronic MI or AI, vigorous septal motion would not be observed because of the occasional presence of relative tricuspid insufficiency, the effects of the long standing burden on the septal myocardium, and compensatory distension of the posterior wall and pericardium.